It is proposed to investigate the response of a complete eyeglass system to impact by various objects on the lens in order to ascertain the fracture potential of such glasses. This topic is of considerable importance in assessing and reducing the hazard to the wearer of eyeglasses from splinters being driven into the eyeball as the result of disintegration of the ophthalmic lens when struck by particles commonly found in industrial, recreational, home and ordinary daily environments. The current FDA requirement for lens prescription sets an artificial standard for their survival under specified drop test conditions; previous preliminary experiments have indicated that one of the most important factors in such survival is the lens-frame interaction which has not been seriously considered (relative to the strength of the lens itself) as a basic consideration in the design of safety standards. The investigation will be conducted by an interdisciplinary team guided by an engineering specialist in impact problems and an optometrist to provide the proper perspective of both areas. The study will involve a coordinated experimental and theoretical approach to determine the history of stress, strain, and deformation in the system so that a better combination of both material and configuration of the lens and supporting structure can be fabricated as a result of the program. The testing phase will comprise projection of strikers onto a variety of lens/frame combinations at speeds commensurate with those found in practice, such as stones thrown up by vehicles or metal cuttings separating from work pieces. The corresponding analytical approaches will utilize the finite element method for the determination of the mechanical response parameters resulting from controlled loading. The effect of various mounting methods, including level configuration and eyewire grooving, on the frangibility of the system will be investigated. The correlation of data and analytical prediction of displacement and stresses from such investigation will permit an assessment of the validity of the model and will then allow the employment of the latter as a design tool to permit the construction of safer and perhaps even cheaper lens-frame combinations.